content: /* ===========================================================
   * JFreeChart : a free chart library for the Java(tm) platform
   * ===========================================================
   *
   * (C) Copyright 2000-2014, by Object Refinery Limited and Contributors.
   *
   * Project Info:  http://www.jfree.org/jfreechart/index.html
   *
   * This library is free software; you can redistribute it and/or modify it
   * under the terms of the GNU Lesser General Public License as published by
   * the Free Software Foundation; either version 2.1 of the License, or
   * (at your option) any later version.
   *
   * This library is distributed in the hope that it will be useful, but
   * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
   * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
   * License for more details.
   *
   * You should have received a copy of the GNU Lesser General Public
   * License along with this library; if not, write to the Free Software
   * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301,
   * USA.
   *
   * [Oracle and Java are registered trademarks of Oracle and/or its affiliates. 
   * Other names may be trademarks of their respective owners.]
   *
   * ------------------
   * LineUtilities.java
   * ------------------
   * (C) Copyright 2008, 2014, by Object Refinery Limited and Contributors.
   *
   * Original Author:  David Gilbert (for Object Refinery Limited);
   * Contributor(s):   -;
   *
   * Changes
   * -------
   * 05-Nov-2008 : Version 1 (DG);
   * 28-Feb-2014 : Added extendLine() (DG);
   *
   */
  
  package org.jfree.chart.util;
  
  import java.awt.geom.Line2D;
  import java.awt.geom.Rectangle2D;
  
  /**
   * Some utility methods for {@link Line2D} objects.
   *
   * @since 1.0.12
   */
  public class LineUtilities {
  
      /**
       * Clips the specified line to the given rectangle.
       *
       * @param line  the line (<code>null</code> not permitted).
       * @param rect  the clipping rectangle (<code>null</code> not permitted).
       *
       * @return <code>true</code> if the clipped line is visible, and
       *     <code>false</code> otherwise.
       */
      public static boolean clipLine(Line2D line, Rectangle2D rect) {
  
          double x1 = line.getX1();
          double y1 = line.getY1();
          double x2 = line.getX2();
          double y2 = line.getY2();
  
          double minX = rect.getMinX();
          double maxX = rect.getMaxX();
          double minY = rect.getMinY();
          double maxY = rect.getMaxY();
  
          int f1 = rect.outcode(x1, y1);
          int f2 = rect.outcode(x2, y2);
  
          while ((f1 | f2) != 0) {
              if ((f1 & f2) != 0) {
                  return false;
              }
              double dx = (x2 - x1);
              double dy = (y2 - y1);
              // update (x1, y1), (x2, y2) and f1 and f2 using intersections
              // then recheck
              if (f1 != 0) {
                  // first point is outside, so we update it against one of the
                  // four sides then continue
                  if ((f1 & Rectangle2D.OUT_LEFT) == Rectangle2D.OUT_LEFT
                          && dx != 0.0) {
                      y1 = y1 + (minX - x1) * dy / dx;
                      x1 = minX;
                  }
                  else if ((f1 & Rectangle2D.OUT_RIGHT) == Rectangle2D.OUT_RIGHT
                          && dx != 0.0) {
                      y1 = y1 + (maxX - x1) * dy / dx;
                      x1 = maxX;
                  }
                  else if ((f1 & Rectangle2D.OUT_BOTTOM) == Rectangle2D.OUT_BOTTOM
                          && dy != 0.0) {
                      x1 = x1 + (maxY - y1) * dx / dy;
                      y1 = maxY;
                  }
                  else if ((f1 & Rectangle2D.OUT_TOP) == Rectangle2D.OUT_TOP
                          && dy != 0.0) {
                      x1 = x1 + (minY - y1) * dx / dy;
                      y1 = minY;
                  }
                  f1 = rect.outcode(x1, y1);
              }
              else if (f2 != 0) {
                  // second point is outside, so we update it against one of the
                  // four sides then continue
                  if ((f2 & Rectangle2D.OUT_LEFT) == Rectangle2D.OUT_LEFT
                          && dx != 0.0) {
                      y2 = y2 + (minX - x2) * dy / dx;
                      x2 = minX;
                  }
                  else if ((f2 & Rectangle2D.OUT_RIGHT) == Rectangle2D.OUT_RIGHT
                          && dx != 0.0) {
                      y2 = y2 + (maxX - x2) * dy / dx;
                      x2 = maxX;
                  }
                  else if ((f2 & Rectangle2D.OUT_BOTTOM) == Rectangle2D.OUT_BOTTOM
                          && dy != 0.0) {
                      x2 = x2 + (maxY - y2) * dx / dy;
                      y2 = maxY;
                  }
                  else if ((f2 & Rectangle2D.OUT_TOP) == Rectangle2D.OUT_TOP
                          && dy != 0.0) {
                      x2 = x2 + (minY - y2) * dx / dy;
                      y2 = minY;
                  }
                  f2 = rect.outcode(x2, y2);
              }
          }
  
          line.setLine(x1, y1, x2, y2);
          return true;  // the line is visible - if it wasn't, we'd have
                        // returned false from within the while loop above
  
      }
      
      /**
       * Creates a new line by extending an existing line.
       *
       * @param line  the line (<code>null</code> not permitted).
       * @param startPercent  the amount to extend the line at the start point
       *                      end.
       * @param endPercent  the amount to extend the line at the end point end.
       *
       * @return A new line.
       * 
       * @since 1.0.18
       */
      public static Line2D extendLine(Line2D line, double startPercent,
                                double endPercent) {
          ParamChecks.nullNotPermitted(line, "line");
          double x1 = line.getX1();
          double x2 = line.getX2();
          double deltaX = x2 - x1;
          double y1 = line.getY1();
          double y2 = line.getY2();
          double deltaY = y2 - y1;
          x1 = x1 - (startPercent * deltaX);
          y1 = y1 - (startPercent * deltaY);
          x2 = x2 + (endPercent * deltaX);
          y2 = y2 + (endPercent * deltaY);
          return new Line2D.Double(x1, y1, x2, y2);
      }
  
  }
  